From WO 2008/131754 A1 a generic, soluble and substantially ring-shaped casting core for forming a cooling channel in a piston of a combustion engine is known. Here, the casting core comprises at least one inflow and at least one outflow. In the region of the inflow and of the outflow, the cooling channel merges into two regions that are arranged approximately parallel to the piston axis and face away from the piston base in each case via a quarter of a circle-shaped core bend, wherein one of the regions merges into a part of the casting core that forms the inflow of the cooling channel, whereas the other part of the casting core merges into the region forming the outflow. In the two regions of the casting core in this case are arranged at a distance from each other which maximally corresponds to double the cross sectional diameter of one of the two regions, as a result of which the through-flow of the cooling oil flowing through the cooling channel is to be accelerated and the cooling of the piston improved.
From DE 10 2004 043 720 A1 a cooling channel with a single inflow opening and two separate outflow openings is known, as a result of which no impairment of the coolant outflow is to occur on the respective outflow opening.
From DE 10 2008 038 324 A1 a piston with a cooling channel is known, which is substantially designed ring-shaped and has two separate inflow openings as well as two separate outflow openings. Between the outflow openings a cross-sectional constriction acting as a choke is provided.
Disadvantageous with casting cores known from the prior art is that on the one hand these are difficult to handle because of their fragility and on the other hand their design often makes possible merely an unsatisfactory cooling of the piston.